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Topic: 1975 CB750 Rear brake hub help (Read 483 times)

Hello, I'm finishing up a custom cb750 build but am running into issues with the rear brake hub. The issue is that the outside of the hub rubs on the outside of the wheel like there is a spacer missing. Looking at the parts fiche it doesn't appear to have a spacer in there but if that's the case then does that mean i have the wrong brake hub for the wheel?

Ok, this is what I got...Measurements taken from the axle shaft opening, from inside to outside edges of the bearing/spacer surfaces.Brake hub- 43mmDrum hub- 180mm (with sprocket side wheel spacer installed) - 168mm (without wheel spacer installed)

What I have looks just like what you have.

I did notice though, mine will rub together if not seated properly. Which leads me to ask, have you checked the fitment/rubbing issue with the axle installed?It's a close tolerance and the axle keeps it aligned properly.

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So I have some measurements to compare to yours. I feel like the drum hub measurement was way off so I included an image to make sure we were measuring the same thing. If we were measuring the same thing then I'm assuming this is not the stock hub for this bike based on the results.

So basically I'm 1.65mm short of hitting the bearing surface and preventing the rubbing issue. I have to get some things machined anyways and was wondering if there is any issue with machining a 3mm spacer to fit between drum bearing and brake panel to fix my problem? I'm helping my friend finish his build he started a year ago and everything is powder coated and re-laced on the wheels so I'd hate to have to start over.

I was thinkin the same about simply adding a washer/spacer to move the brake panel out just a tad. You'd have to figure a way to hold it in place with the drum and brake assembled until you could insert the axle though. Not too difficult, just a thought though.Or maybe machine the outer lip on the drum down to achieve the same clearance?

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